94 Lift Off Exploring the Universe

CHAPTER 1 What's Out There? ZHEE STARED THROUGH THE WINDOW AT THE SPACEPORT RISING UP OUT OF THE ORANGE RAIN-GAS CLOUDS BELOW. SHE HAD NEVER SEEN SUCH NOISE AND FILTH.... In five minutes the ship she was traveling on would touch down in the middle of Shangha-port, one of the busiest spaceports still operating on Old Terra. A funny feeling, this homecoming that wasn't. Zhee knew that she had been born on Old Terra, Earth, one of the last of her work-group, before their section was sent up to Moonblock 9. Not that they'd stayed long on the moon. Zhee was still a baby when her group had moved to Mars after the 65 discovery of uranium on the red planet. Since then, Zhee had spent most of her 94 years working the rich mines on Mars's unwelcoming surface, going on vacation to the pleasure-ships in orbit above.

The long-ago litelltory of green Old Terra remained strong in most people's minds, though, and when news had come through of special return permits for a new ecology project that was under way in Sahara, the desert continent, Zhee had jumped at the chance. She'd worked in Mars's terrible conditions for 70 years now, so she imagined she could cope with a bit of Old Terra desert, no matter what people said. If the project went well, they would take the new technology back to Mars and create a second, more fertile Earth. Looking at the orange storm below, Zhee had to admit that Earth was not what she had imagined... We have no way of knowing whether the future of space exploration will be anything like Zhee's experience, or where present space exploration may lead us, but experiments with living in and exploring space have been going on for over 50 years.

The beginnings of space exploration are tied to the Cold War, when political connpetition between the Soviet Union and the United States moved up into space. Many early achievements were Russian, such as the first rocket to orbit the Earth (1957), the first astronaut (Yuri Gagarin, 1961), and the first woman in space (Valentina Tereshkova, 1963). The USA responded with its Apollo program, which eventually sent Neil Armstrong to become the first man on the moon, in 1969. By the 1970s, however, cooperation was beginning to replace competition, as political relations improved. This led to projects such as the 1998 launch of the International Space Station, to this date the longest- inhabited space station. Manned spaceflights are still limited to the exosphere, the highest level of the Earth's atmosphere. No human has ever gone further than our moon, and manned flights to more distant destinations, such as the planet Mars, are still not possible.

However, the use of unmanned space probes has a very successful history. These missions are mostly fact-finding missions, but they are also used to test space-flight technology for later use in manned flights. They can be either orbiters, which take photos from space, or landers, which take information from the planet's surface. Much of what we now know about our neighboring planets, for example the existence of ice on Mars, has come from successful probe explorations. Rovers are unmanned vehicles that are used to explore planetary surfaces. They have the advantage of being mobile, which means they can travel around and send back information about many areas of a planet. Several countries have successfully landed rovers on Mars. Presently the USA has a rover, Curiosity, exploring the planet. The information these missions send back may one day allow manned missions to Mars.

CHAPTER 2 At Home in Space FOR HUMANS TO CONTINUE TO EXPLORE OUR GALAXY, THE MILKY WAY, WE WILL NEED TO BE ABLE TO LIVE IN SPACE FOR LONG PERIODS OF TIME. Living long-term in a low-gravity or micro-gravity environment like space can have harmful effects on the human body. It can make movement difficult, weaken muscles and bone, and cause changes in our immune system, vision, and taste. Although scientists have learned how to solve these problems through exercise, diet, and medicines, astronauts who spend long periods of time in micro-gravity conditions still find they are very weak when they return to Earth's higher gravity. So far, the record for the longest time spent outside of Earth's atmosphere is held by the Russian astronaut Valeri Polyakov, who stayed on the space station Mir for about 14 months to test effects on the human body. Returning to Earth, Polyakov managed to walk from his spaceship to a chair, to the amazement of everyone there. That same day he is rumored to have said, "We can fly to Mars."

Polyakov's experiences showed that astronauts could spend long periods of time in space without suffering long-term problems, although there are still questions about whether humans could live for many years in this kind of environment. Living in space provides other challenges. Space is almost a vacuum, with neither the pressure nor oxygen to support the human body. The low pressure causes swelling and also a drop in blood temperature. Humans exposed to a vacuum would lose consciousness almost immediately, and exposure of more than 90 seconds is deadly. However, the effects are not as dramatic as some Hollywood movies would have us believe, and experiments on animals show strong recovery from exposure of less than 90 seconds.